Pulsation

I have a 1991 MGM and when I am driving at regular speeds there is a puslation coming from the engine or trans while my foot is on the pedel. It doesn't do it while accelerating though. Any answere??

Also there is jerking and poping coming from the Diff. area while changing into 3 or 4th gears. It does it especially when going back and fourth between gears constantly. Any ideas??

Is it pulsing while you are pushing the brake pedal? If so, your brake rotors need to be turned.

Need a bit more info about the "jerking and popping". Coming from the differential area you say?